4L30E Interchange

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This is the first article I ever had published with Gears magazine. A controversial repair, but it's worked for years now.

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4L30E Interchange

  1. 1. PLAYING WITH FIRE by Jon Rodriguez4L30E Pump Interchange pressure and converter charge issues. 2. Torque converter clutch regulator valve wear. The pulse width modu- lated apply of the converter is con- trolled through the converter clutch regulator valve. You’ve probablyW elcome to the first edition of Playing with Fire. In this new series, we’re going tocover the most common interchangequestions that we receive on the ATRAHotLine. Interchange is an important subjectbecause of the risk verses reward factorthat comes into play. Sometimes a dif-ferent style part can be less expensive,more plentiful, and in some cases suchas this one, improve the durabilityof the transmission. All of which canmake the job more profitable. The risk?Virtually none… as long as you handlethe interchange correctly. In this edition we’re going to lookat how to use a two-valve, on/off-stylelockup pump in place of the four-valve,PWM-style lockup pump in 2000-2004Trooper and Axiom 4L30E transmis-sions. There are two common reasons forpump failure in the PWM-style pumps:1. Pump gear and cavity wear. Any galling or clearances above 0.003” between the outer pump gear and pump body, or between the inner pump gear and crescent, aren’t acceptable. Using a pump with wear in these areas will reduce pump volume and cause line Figure 14 GEARS July 2008
  2. 2. experienced code P1811 — trans- 3.5L engine. The spring behind the TCC con- mission component slipping — in The other part of the system is the trol valve applies 4.5 lbs at working both front- and rear-wheel drive TCC solenoid. Since an on/off-style height. With the valve’s signal land GM transmissions, and the 4L30E lockup solenoid has a resistance of 18- being 0.12”, it’ll take about 38 lbs of is no exception. The cause is wear 20 ohms and the PWM solenoid has a signal oil to switch the valve. in the regulator valve bore, which resistance of 9.5-10.5 ohms, always use With the help of G&S Transmis- reduces clamping force on the deli- the PWM style solenoid or the computer sions in Garden Grove, CA, we moni- cate woven carbon converter clutch will set code P1860 (TCC solenoid elec- tored the TCC solenoid duty cycle in material. trical circuit). a 2000 Trooper with the PWM-style An important consideration is how pump and converter. The computerParts Differences lockup will feel after the changeover. started to signal the solenoid at about This isn’t going to be an in-depth TCC apply will be firmer than it was 40 MPH, and quickly rose to 50% dutylook at the theory of both pumps. with the PWM system. Always discuss cycle. The duty cycle remained at 50%Instead, we’re going to focus on how this with the customer before the conver- through third and fourth gears.to identify the two systems’ parts, and sion; don’t wait until you’re finished towhat you need to change. For those of explain the difference. If you explain ityou who want the “whys” answered, beforehand, the customer will expect thewe’ll discuss that at the end of this difference and appreciate your efforts;article. waiting until later, your explanation CAUTION: Never attempt to cross starts to sound more like an excuse for athe bellhousing, pump plate, and pump condition you weren’t expecting.body. When making this conversion,all three of these components must be Why It Worksthe non-PWM style. These components Figure 5 shows the differences inare completely different; mismatching the pump gasket area. The on/off pumpthem will damage the transmission. is missing the additional machiningRefer to figure 1 to identify the differ- groove for the enable valve in the PWMent parts. pump. This won’t affect gasket sealing The one part that can be modified or hydraulic operation.to work with either system is the input The other difference is the additionshaft. The fluid passages in both shafts of a front seal drainback hole that leadsare identical (figure 2). The one differ- straight to exhaust in the overdrive sec-ence is the PWM-style shaft doesn’t tion. This is actually a better design,have an orifice check valve at the con- because there’s less wormtrack areaverter end (figure 3). If possible, you for crossleaks to allow pressure to getshould use the on/off-style shaft with behind the front seal and cause frontthe valve already installed, but if it isn’t seal popout.available, you can install a new valve Now let’s look at the hydraulicinto the PWM shaft. The check valve is operation: Figure 5 shows the TCCthe same as the one in a 4L60E and is solenoid signal hole is in the identicalavailable from your transmission parts location in both pumps. The differencesupplier. is instead of the solenoid signal oil Never use a shaft without the actuating the enable valve, the torquevalve; that will cause extremely firm converter clutch control valve, and theTCC apply and will damage the TCC isolator valve, it now has only oneclutch material. responsibility: to shift the on/off con- One final difference involves the verter clutch control valve to the apply Figure 2torque converter itself: The PWM con- position.verter uses a woven carbon clutch; theon/off style uses a standard paper clutch(figure 4). Since we’re going to convertlockup apply to an on/off style, there’sno need to spend the extra money onthe woven carbon-style clutch. In fact,the woven carbon is more delicate thanthe paper, and could be damaged if usedwith a firm, on/off apply. The paperclutch style converter can be orderedby using the Rodeo Application with a Figure 3GEARS July 2008 5
  3. 3. 4L30E Pump Interchange 50% is low,because the freshly-built transmission hada solid lockup and thecomputer saw thatthe clutch was fullyengaged at 50%. Thecomputer will con-tinue to increase theduty cycle until theslip drops below 50RPM. On the PWMapplication, the clutchis designed to slip no Figure 4more than 50 RPM,but usually slips under 5 RPM. computer will only set code P1811 with the pump area. Second gear oil provides TCC when the slip is between 250 and 800solenoid feed; basically it’s mainline RPM for seven seconds, and it has to I hope you enjoyed this first edi-pressure. Using our solenoid dyno in occur three times in a row. tion of Playing with Fire as much asthe shop, we found that at 90 PSI — The other code is P0742 — TCC I did researching and writing it. If youwhich would be a light throttle cruising stuck on. This code will only set if TCC have an interchange question you’d likepressure — it takes a 45% duty cycle is commanded completely off and TCC to see addressed here, drop us a lineto achieve 50 lbs of signal oil to the slip is between –20 and 40 RPM for and we’ll see about presenting it in aactuating side of the TCC control valve. two seconds, while throttle opening is future issue.That’s plenty of pressure for our 38-lb above 20%. That isn’t a condition that Until then, remember: If you’revalve to stroke. Voila! Lockup. From this modification should affect. going to play with fire, make sure youthat point, as line goes up, the duty That’s it. Lockup will work beau- pay attention and know exactly whatcycle will need less signal to engage tifully and line pressure will run the you’re doing. That way you won’t getlockup. That’s okay; we still end up same as it did with the original pump. burned!with lockup fully applied. As always, good rebuilding practice “A Special thanks to Raffi at ITC The computer has two codes for dictates that all mating and mounting of Fresno, CA for his help with thislockup ratio problems, and duty cycle surfaces be flat and torqued to specs. article.”isn’t involved with either one. The You shouldn’t have any other problems Figure 56 GEARS July 2008
  4. 4. The Choice is Simple. Genuine ZF. ZF 6-speed (6HP) automatic parts, kits and fluid now available!800.451.2595www.zf.com/na A quality product, a seamless installation, and a satisfied customer – the results of a genuine remanufacturing process and the reasons why ZF makes the choice simple when it comes to choosing a product that will exceed your customers’ expectations. Mile-for-mile, Genuine ZF remanufactured automatic and manual transmissions last longer, perform better, and are of greater value in the long run. Genuine ZF products are remanufactured by expert technicians to exact factory specifications, utilizing only genuine parts and exclusive testing technology. For a ZF Authorized Distributor in your area, visit www.zf.com/na. Driveline and Chassis Technology

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